Abrasive sleeve for rotary abrading machines



c5. L.. sHUsTER ET AL 3,339,319 ABRASIVE SLEEVE FOR ROTARY ABRADING MACHINES Sept. 5, 1967 Filed oom 29, 1964 C5 Sheets-Sheet l *5W GUrdQnL. 5021115592' maw n Howard Wmvna @by z/wmp G. L.. scHUsTl-:R ET AL 3,339,319 E SLEEVE FORV ROTARY BRADING MACHINES Sept. 5, 1967 ABRASIV Filed ont. 29, 1964 I5 Sheets-Sheet 2- oz/ Dardan L. Schuser award W. Gru/na Sept 5, 1967 G. L. SCHUSTER ET AL v ABRASIVE SLEEVE F'OR` ROTARY ABRADING MACHINES 3 Sheets Filed Oct. 29, 1964 v -Sheet 3 "i im Jmwnsw/ Garden L. EaP-meier Hawa@ W STzvz-za United States Patent O 3,339,319 ABRASIVE SLEEVE FOR ROTARY ABRADIN G MACHINES Gordon L. Schuster, Minneapolis, and Howard W. Grivna, Fridley, Minm, assignors to Timesavers Sanders, Inc., Minneapolis, Minn., a corporation of Kansas Filed Oct. 29, 1964, Ser. No. 407,300 3 Claims. (Cl. 51-395) ABSTRACT OF THE DISCLOSURE A sleeve of flexible material having suflicient tensile strength to successfully resist centrifugal force incident to rotation of the sleeve when mounted on a drum rotating at high speed, has an abrasive outer surface, arranged in circumferential axially adjacent bands, certain of which are more abrasive than the rest.

This invention relates to abrading machines generally, and refers more particularly to machines for imparting a desired effect or appearance to any surface by abrasion. Although the invention is especially concerned with the treatment of plywood, hard board and fiber-board wall panels and the like, as Well as rough lumber, it is not limited to the treatment of such products, but instead will be found useful in abrasive treatment of any surface.

Thus it is an object of this invention to provide an improved abrading machine which has great versatility and can be quickly and easily adapted to the treatment of any generally flat surface and to impart to such surface any desired effect or appearance.

A particular object of this invention is to provide an abrading machine which is as useful and effective as a planer to dress lumber to size as it is to impart to any generally flat surface a special appearance or effect-like, for instance, that of re-sawn lumber, wherein striations such as those produced by a band saw extend transversely across the grain of the wood.

In this connection it is a feature of this invention that any desired surface effect or appearance can be produced at very rapid rates of production, many times greater than heretofore possible even with single purpose machines especially designed to produce only one specific effect or appearance.

To achieve this desired versatility in an abrading machine, the invention contemplates the provision of a workperforming rotor having a readily changeable or replaceable abrading surface, and the capability of utilizing centrifugal force due to high speed rotation of the rotor, to.

keep that surface truly concentric with the axis of the rotor.

More specifically, it is an object of the present invention to provide an improved work-performing rotor for an abrading machine wherein a sleeve with abrasive particles bonded to its outer surface in any desired pattern and of any selected grit size, is removably mounted on a power driven drum, and held thereon by radial expansion of the peripheral portion of the drum in response to centrifugal force resulting from high speed rotation of the drum.

Another object of this invention is to provide an iniproved work-performing rotor for abrading machines which consists essentially of a relatively flexible though 3,339,319 Patented Sept. 5, 1967 ICC abrasive sleeve, but also forms itself and the sleeve thereon into a truly cylindrical shape when the drum turns at high speed.

Still another object of this invention is to provide an improved work-performing rotor for abrading machines, wherein a thin-Walled abrasive sleeve removably mounted on a drum to provide the actual working surface of the rotor is kept from overheating by streams of cooling air flowing through grooves in the drum and along the inrer surface of the sleeve from one end thereof to the ot er.

In this connection it is also a feature of the invention that the grooves which provide passages for cooling air are so disposed that they contribute to the radial expansibility of the peripheral portion of the drum.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate one complete example of the physical embodiment of the invention, constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIGURE l is a side view of the elements of an abrading machine, which need to be shown to illustrate this invention;

FIGURE 2 is a top View of the work-performing rotor of the abrading machine;

FIGURE 3 is a perspective view of one end portion of the abrading sleeve of the machine, shown removed from the drum on which it, or one like it, is mounted in the operative condition of the machine;

FIGURE 4 is a cross sectional view 4at a greatly magnified scale, through a portion of the abrading sleeve;

FIGURE 5 is a fragmentary cross sectional view through a segment of the work-performing drum and the abrading sleeve thereon;

FIGURE 6 is a perspective View of a portion of a panel that has been acted upon with the abrading sleeve of FIG- URE 3; and

FIGURE 7 is a diagrammatic top plan view of an abrading machine equipped with a plurality of work-pen substantially inelastic sleeve having an abrasive outer surforming rotors of this invention, and illustrating the manner in which a re-sawn effect may be imparted to the surface of a relatively large wall panel or similar product.

Referring now particularly to the accompanying drawings in which like numerals indicate like parts, the 11umeral 8 indicates generally the improved work-performing rotor of this invention. As in conventional abrading or sanding machines in which the abrading is done by a rotating drum with an abrasive surface, the rotor 8 is mounted in the frame of the machine by being journalled in bearings 9, more or less diagrammatically illustrated in FIGURE 2. To provide unrestricted access to at least one end of the rotor, the bearing at that side of the machine is arranged to be opened and swung to a position clear of the rotor. This may be done in any conventional manner, and by the same token any suitable means may be employed to drive the rotor at high speed.

A pair of hold-down shoes 10 embrace the rotor 8. These shoes have smooth-surfaced flat bottoms 11 which lie in a common plane and position the surface of the work to be acted upon with respect to the rotor. To this end, the hold-down shoes 10 and the rotor 8 are relatively vertically adjustable, the adjustment being effected in any conventional way.

supporting roller 13 to hold the workpiece W (which may be a wall panel, a piece of rough lumber or any other product) against the underside of the hold-down shoe, and preferably the rollers 13 are biased upwardly by springs indicated diagrammatically as at 14. There is also a work-supporting roller 15 directly beneath the rotor 8 to support the work and hold it against the rotor; and paired feed rolls 16-17 are located both upstream and downstream of the rotor to advance the work through the machine.

All of the general structure of the machine described thus far is conventional; the invention being concerned only with improvement of the work-performing rotor 8, and more specifically with the way a readily replaceable abrasive surface is provided for the rotor and true concentricity of that abrasive surface to the axis of rotation is assured. To this end, the rotor comprises a drum 20 consisting of a rigid cylindrical shell or core 21 and a relatively elastic and/ or resilient annulus which forms the peripheral portion 22 of the drum. The shell or core 21 may be a length of steel tubing with plugs in the ends thereof, and a 4shaft 23 passing axially therethrough; and the peripheral portion 22 may be a tube of rubber or rubber-like material, securely bonded to the steel tube. A sleeve 24 with cutting or abrasive means 25 bonded to its outer surface encircling the elastic peripheral portion 22 completes the rotor.

The sleeve 24 is tightly held to the drum 20 during high speed rotation thereof, but is readily removable from the drum when the rotor is at rest. This very desirable feature results from the fact that the peripheral portion 22 of the drum has the property of expanding in diameter in response to centrifugal force due to high speed rotation of the drum, while the abrasive sleeve 24 is strong enough to resist enlargement at the operating speeds involved. Hence, as will be apparent, if the sleeve is slightly larger in girth than the peripheral portion of the drum when at rest, the sleeve can be slipped onto and olf the drum, providing one of its bearings is moved out of the way; and will be tightly gripped when the machine is in operation and the drum is rotating.

Although the fact that the peripheral portion 22 of the drum is formed of elastic material alone will permit some radial expansion thereof in response to centrifugal force, the desired expansion is assured by the provision of grooves 26 in the peripheral portion 22. These grooves extend longitudinally of the drum and are equally spaced around its circumference, but from the standpoint of promoting radial expansion of the drum the signicant fact about the grooves is that their center lines are not radial to the axis of the drum. Instead, and as best shown in FIGURE 5, the center lines of the grooves (the dotted lines CL) are all inclined in one direction and to the same extent with respect to any radian to the axis of the drum. As a result, the portion or land 27 between every pair of adjacent grooves has a part 28 thereof, indicated by closer cross hatching, which overlies a groove and hence is not as firmly supported against outward displacement by centrifugal force as the remainder of the land 27.

Also, as best shown in FIGURE 5, all of the grooves have the same size and shape, their side walls 26 prefersure of the expanded peripheral portion 22 of the drum, and the flexibility needed to conform to the cylindrical shape of the drum when the sleeve is gripped by its expanded peripheral portion. In practice good results have been obtained with sleeves made of sheet steel 20-30 thousandths of an inch thick, rolled into a tube and butt welded. Seamless tubes of the correct size and wall thickness could also be used.

The cutting or abrasive means 25 on the outer surface of the sleeve 24 preferably consists of particles of tungsten carbide bonded in any suitable way to the sleeve, and as can be readily understood, the particles may be of different sizes and may be arranged or distributed over the surface of the sleeve to produce a wide variety of effects or appearances on the surface of the Work acted upon by the revolving rotor. Thus, as shown in FIGURE 3, the abrasive outer surface of the sleeve may have axially spaced bands 30 of particles that are coarser than those covering the remainder of the sleeve surface. This would produce parallel grooves in the surface of the work acted upon, like the grooves 31 in the wall panel shown in FIGURE 6.

Another arrangement of the tungsten-carbide particles could produce a re-sawn effect upon the surface acted upon, providing the work Was fed through the machine crosswise, i.e. against the grain rather than With -the grain. In this case, though, it is desirable to employ a group of abrasive rotors 32 arranged in two staggered rows, as diagrammatically shown in FIGURE 7, or end-to-end on a common shaft. Where the staggered arrangement is used, all -of the rotors are of the same type and con struction as described and any suitable means may be employed to mount and ydrive them. With the arrangement shown in FIGURE 7, a re-sawn effect can be produced at very high Iproduction rates; for instance, fourby-eight foot panels can be given the re-sawn effect at speeds as high as four hundred feet per minute, the only limiting factor being the capacity of the feeding mechanism.

A significant feature of this invention not yet described resides in the fact that the grooves 26 not only promote radial expansion of the peripheral portion 22 of the rotor, but also provide means for cooling the abrasive sleeve. To this end, the grooves 26 are open at the opposite ends of the drum, permitting air to ow therethrough from one end of the rotor to the other. Such air flow could lbe exteriorly induced, as by having one end of the drum operating in a pressurized zone, while at the other end of the rotor a low pressure zone is maintained; but by arranging the grooves spirally as they are, the desired air flow through the passages formed conjointly by the walls of the grooves and the inner surface of the sleeve, is self-induced. By virtue of this spiral disposition of the grooves on the drum, one end of each groove leads the other as it is carried around its circular orbit, with the result that air is sucked into one end 0f the groove and expelled from the other.

From the foregoing description, taken in connection with the accompanying drawings, it will be apparent to those skilled in the art that this invention provides an abrading machine of great versatility and one which is capable of very high production rates, whether the machine is used to impart a re-sawn effect to the surface of Wall panels, or to impart any other texture or appearance to the surface of any workpiece, product or the like that can be fed through the machine. It will also be obvious that with appropriate modification of the means for supporting the work and feeding it through the machine, the same abrasive covered sleeve and drum can `be used to dress or plane rough lumber.

What is claimed as our invention is:

1. A rotary abrading element adapted to be mounted on a drum, comprising:

(A) a sleeve of flexible material having sufficient tensile strength to successfully resist the centrifugal force incident to rotation of the sleeve when mounted `on a Idrum rotating at high speed; and

(B) circumferential bands of abrasive particles bonded to the outer surface of the sleeve, certain of said bands being more abrasive than the rest.

2. The abrading element of claim 1, wherein the more abrasive bands are axially spaced from one another and narrower than the intervening less abrasive bands.

3. The abrading element of claim 2, wherein the narrow axially spaced more abrasive bands project above the adjacent less abrasive bands, so that said narrow bands form parallel grooves in the surface 0f Work acted upon by the abrading element.

References Cited UNITED STATES PATENTS Landis 51-402 X Hope 51-375 Stratford 51-398 Larson 51-374 Larson 51--374 Highberg 51-283 X ROBERT C. RIORDON, Primary Examiner. D. G. KELLY, Assistant Examiner. 

1. A ROTARY ABRADING ELEMENT ADAPTED TO BE MOUNTED ON A DRUM, COMPRISING: (A) A SLEEVE OF FLEXIBLE MATERIAL HAVING SUFFICIENT TENSILE STRENGTH TO SUCCESSFULLY RESIST THE CENTRIFUAL FORCE INCIDENT TO ROTATION OF THE SLEEVE WHEN MOUNTED ON A DRUM ROTATING OF THE SLEEVE WHEN MOUNTED (B) CIRCUMFERENTIAL BANDS OF ABRASIVE PARTICLES BONDED TO THE OUTER SURFACE OF THE SLEEVE, CERTAIN OF SAID BANDS BEING MORE ABRASIVE THAN THE REST. 